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Copper Shark
The Copper Shark is a species of requiem shark, family Carcharhinidae, and the only member of its genus found mostly at temperate latitudes. While not noted as being especially dangerous to humans, the copper shark has been responsible for a number of non-fatal attacks, particularly on spear fishers and bathers. This species is valued by commercial and recreational fisheries throughout its range, and utilized as food. It is very susceptible to population depletion due to its low growth and reproductive rates, and its numbers are believed to have declined in some areas. As a result, the International Union for Conservation of Nature (IUCN) has assessed it as Near Threatened. Description The copper shark has a slender, streamlined body with a slightly arched profile just behind the head. The snout is rather long and pointed, with the nostrils preceded by low flaps of skin. The round, moderately large eyes are equipped with nictating membranes (protective third eyelids). The mouth has short, subtle furrows at the corners and contains 29–35 upper tooth rows and 29–33 lower tooth rows. The teeth are serrated with single narrow cusps; the upper teeth have a distinctive hooked shape and become more angled towards the corners of the jaw, while the lower teeth are upright. The upper teeth of adult males are longer, narrower, more curved, and more finely serrated than those of adult females and juveniles. The five pairs of gill slits are fairly long. The pectoral fins are large, pointed, and falcate (sickle-shaped). The first dorsal fin is tall, with a pointed apex and a concave trailing margin; its origin lies about even with the tips of the pectoral fins. The second dorsal fin is small and low, and positioned about opposite to the anal fin. There is usually no ridge between the dorsal fins. The caudal fin has a well-developed lower lobe and a deep ventral notch near the tip of the upper lobe. This species is bronze to olive-gray above with a metallic sheen and sometimes a pink cast, darkening towards the fin tips and margins but not conspicuously so; the color fades quickly to a dull gray-brown after death. The underside is white, which extends onto the flanks as a prominent band. The copper shark is easily mistaken for other large Carcharhinus''species, particularly the dusky shark (''C. obscurus), but can be identified by its upper tooth shape, absent or weak interdorsal ridge, and lack of obvious fin markings. Habitat Copper sharks can be found from the surf zone to slightly beyond the continental shelf in the open ocean, diving to depths of 100 m (330 ft) or more. This species commonly enters very shallow habitats, including bays, shoals, and harbors, and also inhabits rocky areas and offshore islands. It is tolerant of low and changing salinities, and has been reported from estuaries and the lower reaches of large rivers. Juveniles inhabit inshore waters less than 30 m (98 ft) deep throughout the year, while adults tend to be found further offshore and regularly approach the coast only in spring and summer, when large aggregations can be readily observed in shallow water. Food The copper shark feeds more towards the bottom of the water column than the top, consuming cephalopods, including squid (Loligo spp.), cuttlefishes, and octopus; bony fishes, including gurnards, flatfishes, hakes, catfishes, jacks, Australian salmon, mullets, sea breams, smelts, tunas, sardines, and anchovies; and cartilaginous fishes, including dogfish sharks (Squalus spp.), stingrays, skates, electric rays, and sawfishes. Cephalopods and cartilaginous fishes become relatively more important food for sharks over 2 m (6.6 ft) long. Young sharks also consume scyphozoan jellyfish and crustaceans, including mud shrimps (Callianassa) and penaeid prawns. It does not attack marine mammals, though has been known rarely to scavenge on dolphins that had succumbed to fishing nets. The predominant prey of this species off South Africa is the southern African pilchard (Sardinops sagax), which comprise 69–95% of its diet. Category:Fish Category:Meat Eater Category:Cold Blooded Category:Viviparous